Ok.. could you give more information, what do you mean blank? Does it power off, is just the screen turning off, is it the flash that happens when Windows 7 or Vista shows security notice...
More would be nice to help you with this one.
My computer has XP on it. I can have everything up and running and when I connect my phone to the USB cable all of my icons and task bar disappear. As soon as I disconnect the phone they reappear. And sometimes it just locks up the computer and nothing comes back. I kept messing with it, connecting and disconnecting, and finally it didn't do it so that I could pull a video off my phone.
Have you installed the device drivers for the devices because it sounds like the device is causing the explorer to close when the device is plugged in? Try rebooting device and boot into safe mode by pressing F8 during boot process and then plug the phone into the pc and see if it still does it, this can isolate software as a issue..
After booting back into windows...
Make sure the drivers are installed from http://www.motorola.com/Support/US-EN/Support-Homepage/Software_and_Drivers/USB-and-PC-Charging-Driv...
drivers???? maybe a bad usb port. try another one or even try on a different computer.
i use xphome/sp2 & drivers were installed for the dx the 1st time i plugged into the usb port.
Drivers can cause a system to crash when plugged in but your ideal about the usb being bad could cause issues also but since the PC is simply causing the Start bar and icons both of these ideals is a shot in the dark because this isnt a common problem..
To test the usb they could simply try another port but I really dont think this is it..
I had this happen before when I was transferring music to my iTunes account. Sometimes the computer blanked out and if I waited a bit it came back on. I did go and download a driver. The 5.4 Motorola something or another. And it may be that I had not given it a chance to get fully running before I tried again. Because it was later after that, that it started working. But it wasn't working at first right after downloading. So, is that explained well enough? I know, clear as mud huh? 🙂